Analise da estrutura populacional dos camarões-juvenis da família Penaeidae acessível a pesca artesanal no estuário dos Bons Sinais e praia de Zalala, Zambézia

Abstract

The present study aimed to analyze the population structure and Fulton’s condition factor of juvenile shrimp from three species (Fenneropenaeus indicus, Metapenaeus monoceros, and Parapenaeopsis sculptilis) in different sections of the Bons Sinais Estuary and Zalala Beach. To conduct the study, data from catches obtained from artisanal beach-seine fishing and "chicocota" nets, provided by the National Institute of Oceanography of Mozambique (InOM), former Fisheries Research institute, were used. The data spanned from June to November 2018 and January to May 2019. An exploratory analysis of the data was carried out for all sections with a minimum sample size (n> 30). Length class intervals (Lc) were defined for individuals of each species, and the frequency of occurrence of species in each section was determined. Subsequently, histograms of species distribution by length class were created, Fulton’s condition factor was determined, and the weight-length relationship was analyzed for each section and species. The results showed that the population structure of the three shrimp species varied across the different sections analyzed. For Fenneropenaeus indicus, the length peaks in the Quelimane, Gazelas, and Zalala sections were observed in the 11-17 mm class (20%), 9-23 mm class (15%), and 13-21 mm class (20%), respectively. For Metapenaeus monoceros, abundances were recorded in the 10-18 mm class (20%), and 7-9 mm and 14-16 mm classes (20% and 40%) for the Quelimane, Gazelas, and Zalala sections, respectively. For Parapenaeopsis sculptilis, the highest frequency of individuals was observed in the 17-23 mm, 12-22 mm, and 19-33 mm classes for the Quelimane, Gazelas, and Zalala sections, respectively. The growth patterns of the species differed: all three species exhibited isometric growth in the Quelimane and Gazelas sections (b = 1.66), while Fenneropenaeus indicus and Metapenaeus monoceros showed positive allometric growth (b = 2.80) in the Zalala section. In contrast, Parapenaeopsis sculptilis exhibited negative allometric growth in the Zalala section (b = 0.33). Regarding the nutritional status of the shrimp, the average Fulton’s condition factor values for Fenneropenaeus indicus in all sections were around ~0.10, for Metapenaeus monoceros it was 0.99 in the Quelimane section, and for the Gazelas and Zalala sections it was ~0.11. Finally, for Parapenaeopsis sculptilis, the values were also around ~0.10 in all sections, indicating poor nutritional status for the species studied, except for Metapenaeus monoceros in the Quelimane section. This study provides relevant information on areas with higher juvenile concentrations, helping managers better plan their activities, which can contribute to the conservation of sensitive ecosystems for penaeid shrimp species. Additionally, the study can support the development of ecosystem-based management policies for fisheries, particularly for community-based fishery management councils.